U.S. patent application number 13/512371 was filed with the patent office on 2012-11-29 for compaction device and method for compacting ground.
Invention is credited to Hans-Peter Ackermann, Peter Janner.
Application Number | 20120301221 13/512371 |
Document ID | / |
Family ID | 42814109 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120301221 |
Kind Code |
A1 |
Ackermann; Hans-Peter ; et
al. |
November 29, 2012 |
COMPACTION DEVICE AND METHOD FOR COMPACTING GROUND
Abstract
A compaction device includes at least one traveling drum
rotatable about a drum shaft and having vibration exciters
including unbalanced masses rotating out of phase by 180 degrees in
the same direction of rotation and generating an oscillation torque
about the drum shaft, and having a drive shaft running coaxial to
the drum shaft for driving the vibration exciters. The drum is
divided at least once and each drum part includes at least two
coupled vibration exciters mounted at a distance from the drum
shaft in the drum.
Inventors: |
Ackermann; Hans-Peter;
(Tirschenreuth, DE) ; Janner; Peter; (Krummennaab,
DE) |
Family ID: |
42814109 |
Appl. No.: |
13/512371 |
Filed: |
November 29, 2010 |
PCT Filed: |
November 29, 2010 |
PCT NO: |
PCT/EP10/68418 |
371 Date: |
August 10, 2012 |
Current U.S.
Class: |
404/75 ;
404/117 |
Current CPC
Class: |
E01C 19/282 20130101;
E02D 3/074 20130101; E01C 19/286 20130101 |
Class at
Publication: |
404/75 ;
404/117 |
International
Class: |
E01C 19/38 20060101
E01C019/38 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2009 |
DE |
102009055950.7 |
Apr 21, 2010 |
DE |
202010005962.3 |
Claims
1. A compaction device, comprising: at least one traveling drum
rotatable about a drum shaft, coupled vibration exciters generating
an oscillation torque about the drum shaft, said vibration exciters
having unbalanced masses rotating out of phase by 180 degrees in a
same direction of rotation, and having a drive shaft running
coaxial to the drum shaft for driving the vibration exciters.
wherein the drum is divided into at least two drum parts, and
wherein each drum part comprises at least two coupled vibration
exciters mounted in the drum at a distance from the drum shaft.
2. The compaction device according to claim 1, wherein the drive
shafts for the vibration exciters of each of the at least two drum
parts are mechanically coupled or, via a control means, are
adjusted to be in-phase so that the vibration exciters of all drum
parts oscillate in synchronism also in case of a turning of the
drum parts relative to each other.
3. The compaction device according to claim 1, wherein the drive
shafts for the vibration exciters of adjacent drum parts are
mechanically coupled via a transmission, and wherein said
transmission is operative to transmit a rotation and respectively a
drive torque of a drive shaft with a correct phase, to a following
drive shaft of a drum part.
4. The compaction device according to claim 3, wherein the
transmission for coupling the at least two drive shaft parts is one
of a planetary gear transmission, a spur gear transmission, and a
bevel gear transmission.
5. The compaction device according to claim 1, wherein the drum is
of a two-part design and each of the at least two drum parts
comprises a traveling drive of its own, the at least two drum parts
being connected to each other in a manner allowing them to be
turned coaxially relative to each other.
6. The compaction device according to claim 4 wherein the planetary
gear transmission comprises at least two planetary gear sets.
7. The compaction device according to claim 6, wherein the
planetary gear transmission comprises two planetary gear sets
having a common planetary carrier, wherein ring gears of the
planetary gear sets are respectively connected to a drum part for
common rotation therewith, and respective drive shaft parts are
connected to respective sun gears of the planetary gear sets.
8. The compaction device according to claim 7, wherein the drive
shaft part of each of the at least two drum parts is operative to
drive, via a gear transmission, the at least two vibration
exciters.
9. The compaction device according to claim 8, wherein a drive for
driving the unbalanced masses is one of a belt transmission and a
chain drive.
10. The compaction device according to claim 3, wherein a drive for
driving the vibration exciters is a toothed-belt transmission
comprising a toothed belt for driving toothed-belt pulleys coupled
with unbalanced masses.
11. The compaction device according to claim 9, wherein the drive
is a belt transmission with a belt guiding arrangement allowing for
reversal of the direction of circulation and for a reciprocal
transmission ratio toward the planetary gear transmission.
12. The compaction device according to claim 11, wherein a
transmission ratio of the belt transmission and a transmission
ratio of the planetary gear transmission together result in a
transmission ratio of 1:1.
13. The compaction device according to claim 9, wherein a
multi-stage planetary gear transmission and a belt transmission
without reversal of rotational direction and without reciprocal
transmission ratio toward the planetary gear transmission are
provided.
14. The compaction device according to claim 10, wherein the
vibration exciters comprise unbalanced masses and said unbalanced
masses comprise unbalanced plates being laterally fastened to
toothed-belt pulleys of the toothed-belt transmission and having a
radially outward flank which in a predetermined starting position
is in alignment with the toothed belt of the toothed-belt
transmission if a rotational angle displacement between the two
toothed-belt pulleys driven by the toothed-belt transmission
corresponds to a desired value.
15. The compaction device according to claim 10, wherein a belt
tensioning device is operative to tension the belt for driving the
unbalanced masses and respectively of the pulleys with the aid of
an eccentrically displaceable bearing pin.
16. The compaction device according to claim 15, wherein said belt
tensioning device comprises an eccentric adjustment pin for turning
said eccentric bearing pin.
17. The compaction device according to claim 9, wherein the belt
transmission comprises pulleys which are coaxial and concentric
with a rotational axis of the unbalanced masses and whose weight
distribution does not extend with rotational symmetry with respect
to the rotational axis of the unbalanced masses.
18. The compaction device according to claim 17, wherein recesses
in the material of the toothed-belt pulley, being not symmetrical
with the rotational axis of the unbalanced masses, effect a
non-rotationally symmetric weight distribution and form a negative
unbalanced mass.
19. The compaction device according to claim 10, wherein at least
one of a plurality of unbalanced plates fastened to at least one of
the pulleys, and asymmetrically arranged screws form an unbalanced
mass, said screws to being also adapted for attachment of the
unbalanced plates.
20. The compaction device according to claim 1, wherein, for
accommodating rolling bearings of the unbalanced masses,
cantilevered pivot pins are provided, said rolling bearings
preferably being arranged centrically to a radial belt force and a
centrifugal force of the unbalanced masses.
21. A method for the compacting of ground by means of a drum of a
compacting device, wherein, with the aid of at least one vibration
exciter comprising rotating unbalanced masses, compacting
vibrations of the drum are generated, comprising using a divided
drum with two drum halves, wherein the unbalanced masses of the
vibration exciters in each of the two drum halves are rotated by a
same angle with respect to a phase position as in a turning of the
two drum halves relative to each other, so that a synchronization
of the oscillatory movement of the two drum halves is obtained even
if the drum halves have been turned relative to each other.
Description
[0001] The invention relates to a compaction device for the
compacting of ground according to the precharacterizing part of
claim 1, and a method for the compacting of ground according to
claim 21.
[0002] Compaction devices are known e.g. in the form of a road
roller.
[0003] With the aid of a road roller, ground areas, e.g. asphalt
surfaces, can be compacted across large surface areas. In order to
guarantee the load-bearing capacity and durability of the ground,
sufficient compaction is required. In the compaction performed by
road rollers, a distinction is made between a dynamic and a static
functionality. In case of a dynamic functionality, the compaction
is effected by movement, and in case of a static functionality, the
compaction is effected by the weight of the road roller.
[0004] A road roller can be a self-propelled vehicle and comprises
at least one drum.
[0005] When negotiating curves with the drum of a compaction device
in the form of a road roller, there exist an inner and an outer
curve radius of the drum at the lateral ends of the drum. At the
outer-curve edge of the drum, due to the longer distance that is
being covered there, the speed is higher than at the inner edge.
With increased steering angle and a resultant smaller curve radius,
the distance between said two speeds will become larger. Since,
however, a drum cannot rotate with different peripheral speeds on
its lateral ends, the drum will in the middle of its width be
rolling on the underlying ground or soil, whereas, on the outer
edge regions of the drum, sliding movements (slippage) will occur
between the asphalt and the rolling surface of the drum. For this
reason, it appears useful to divide the drum and to drive both
halves independently from each other so that, due to the smaller
width of the divided drum, the above compulsory effect can be
reduced.
[0006] Oscillation drums, in contrast to vibration drums, are not
produced in a divided configuration because the technical
realization is distinctly more difficult. The synchronization of
the unbalanced masses generating the centrifugal forces must be
guaranteed at all times, particularly also in case of a turning of
the drums relative to each other.
[0007] In a known oscillating roller according to WO 82/01903, two
synchronously rotating imbalance shafts are provided which are
driven via a central shaft by means of toothed belts. Thereby, a
rapidly changing forward/rearward rotating movement is imposed on
the roller. As a result, the rotating roller will never be lifted
from the underlying ground.
[0008] From WO 82/01903 (FIG. 5), there can be gathered four
typical operational state of the oscillation system of an undivided
oscillation drum of the state of the art. From left to right, the
positions of the unbalanced masses are shown as rotated in
respective steps of 90.degree. (phase-shifted).
[0009] Because of the coupled drive, the two unbalanced masses
(imbalance weights) will rotate in the same sense. While, in the
operational states in the left-hand views in FIG. 5, the
centrifugal forces will eliminate each other, the rotational moment
in the views on the right-hand side (FIGS. 5B, 5D), due to the
directions of the centrifugal forces F and the lever arms x, will
be
M=2.times.xF
in the clockwise (FIG. 5B) and respectively the anticlockwise
direction (FIG. 5D).
[0010] Thus, with each revolution of the imbalanced shaft, the drum
will undergo a slight turn to the left and to the right and will
start to oscillate about the rotational axis M of the drum.
[0011] In vibration drums, dividing the drum is already known
because its technical realization is easy. FIG. 2 of the present
description shows a sectional view of a divided vibration drum. The
two drum parts 2a,2b are screwed to each other via a rotary
connection. Here, the unbalanced masses 3 for both drum parts 2a,2b
are arranged on the central imbalanced shaft 31 which is driven by
a hydraulic engine 7. When a curve is negotiated and the drum parts
2a,2b are thus turned relative to each other, nothing will change
about the vibration of the two drum parts 2a,2b relative to each
other, i.e. both drum parts 2a,2b will vibrate in synchronism.
[0012] A simple configuration with a continuous central shaft 33
for driving the unbalanced masses 3 as in a vibration drum, is
shown in FIG. 3 for an oscillation drum. This approach cannot solve
the phase problem for the following reasons:
[0013] When the drum parts 2a,2b (roller surfaces) are being turned
relative to each other, e.g. while a curve is being negotiated, the
position of the unbalanced shafts 31a,31b relative to each other
will change because the imbalance shafts 31a,31b are supported in
the respective drum parts 2a,2b. Since the unbalanced masses 3,
which are driven by toothed belts 32 by a central shaft 33, will
maintain their orientation, the direction of the effectiveness of
the force in the turned drum part 2a,2b will each time be shifted
(FIG. 4 to FIG. 7).
[0014] For better representation of the arrangement of the toothed
belts of FIG. 4 to FIG. 7, the described arrangement of the toothed
belts is shown in perspective view in FIG. 3.
[0015] FIG. 4 and FIG. 5 show the two drum parts 2a,2b prior to
being turned. In FIG. 6 and FIG. 7, the drum parts 2a,2b are shown
after drum part 2b has been turned by 90.degree..
[0016] For explanation, it be assumed that the drum part 2a does
not change its position while the drum part 2b continues being
turned by 90.degree.. For visualization, also the central rotating
shaft is shown in a snapshot and thus is virtually at a standstill.
As depicted in FIG. 7, the two unbalanced masses of the right-hand
drum part 2b have now been positioned above each other. Since the
drive shaft 33 in the center of the drum is at a standstill, the
toothed belt 32 during the rotation of drum part 2b has been
rolling on the central drive pulley 21 and did not change the
orientation of the unbalanced masses 3. However, due to the new
positions of the unbalanced masses 3, the centrifugal forces will
now initiate, with maximum leverage, a moment which will cause the
drum part 2b to rotate. In the position in FIG. 6, on the other
hand, no moment is generated since the effective leverage is
zero.
[0017] The described problematics has the consequence that the drum
parts 2a,2b cannot oscillate in synchronism. In the extreme case,
when the two drum parts 2a,2b operate exactly contrarily to each
other, thrust movements will occur in the gap between the drum
parts 2a,2b and in the adjacent regions, so that the asphalt
surface will be torn open. Depending on the turning of the drum
parts 2a,2b relative to each other, phase errors from 0 to
180.degree. may occur. Already phase errors from 10 to 20.degree.
would shear off the asphalt at the joint between the drum parts
2a,2b.
[0018] Thus, it is an object of the invention to provide a
vibration device and respectively method for the compacting of
ground which is free of the above described problems.
[0019] According to the invention, the above object is achieved by
the features defined in claims 1 and 21, respectively.
[0020] According to the invention, it is provided, in a compaction
device comprising at least one traveling drum rotatable about a
drum shaft, coupled vibration exciters for generating an
oscillation torque about the drum shaft, said vibration exciters
having unbalanced masses rotating out of phase by 180 degrees in
the same direction of rotation, and having a drive shaft running
coaxial to the drum shaft for driving the vibration exciters, that
the drum is divided at least once and that each drum part comprises
at least two coupled vibration exciters mounted in the drum at a
distance from the drum shaft.
[0021] In this arrangement, the respective vibration exciters are
supported in the respective drum parts.
[0022] Preferably, it is provided that the drive shafts for the
vibration exciters of the individual drum parts are mechanically
coupled or via a control means are adjusted to be in-phase so that
the vibration exciters of all drum parts will oscillate in
synchronism also in case of a turning of the drum parts relative to
each other.
[0023] The controlling can be performed electrically,
electronically or hydraulically/pneumatically.
[0024] The drive shafts for the vibration exciters of the adjacent
drum parts can be mechanically coupled via a transmission, said
transmission being operative to transmit the rotation and
respectively the drive torque of a drive shaft with correct phase
to the following drive shaft of the drum part.
[0025] The transmission for coupling the drive shaft parts can be a
planetary gear transmission or a spur gear transmission or a bevel
gear transmission.
[0026] The drum is of a two-part design, and each drum part
comprises a traveling drive of its own, the two drum parts being
connected to each other in a manner allowing them to be turned
coaxially relative to each other.
[0027] A planetary gear transmission, preferably being of the
insertable type, can comprise at least two planetary gear sets.
[0028] Said planetary gear transmission made of two planetary gear
sets can comprise a common planet carrier, with ring gears of the
planetary gear sets being respectively connected to a drum part for
common rotation therewith, and the respective drive shaft parts
being connected to the respective sun gears of the planetary gear
sets.
[0029] The drive for driving the unbalanced masses can be a belt
transmission or a chain transmission.
[0030] The drive for driving the vibration exciters preferably is a
toothed-belt transmission with omega loop, said toothed-belt
transmission driving toothed-belt pulleys coupled with unbalanced
masses.
[0031] The drive preferably is a belt transmission with a belt
guiding arrangement allowing for reversal of the direction of
circulation and for a reciprocal transmission ratio toward the
planetary gear transmission.
[0032] The transmission ratio of the belt transmission and the
transmission ratio of the planetary gear transmission shall
together result in a transmission ratio of 1:1.
[0033] There can also be provided a multi-stage planetary gear
transmission and a belt transmission without reversal of rotational
direction and without reciprocal transmission ratio toward the
planetary gear transmission.
[0034] The vibration exciters comprise unbalanced masses and said
unbalanced masses preferably comprise unbalanced plates being
preferably laterally fastened to the pulleys of the toothed-belt
transmission and having a radially outward flank which in a
predetermined starting position is in alignment with the belt of
the belt transmission if the rotational angle displacement between
the two imbalance shafts and respective pulleys corresponds to the
desired value. Preferably, the belt transmission is a toothed-belt
transmission.
[0035] A belt tensioning device can tension the belt for driving
the unbalanced masses and respectively of the pulleys with the aid
of an eccentrically displaceable bearing pin for the pulley.
[0036] Said belt tensioning device can comprise an eccentric
adjustment pin for turning and arresting said eccentric bearing
pin.
[0037] The belt transmission can comprise pulleys which are coaxial
and concentric with the rotational axis of the unbalanced masses
and whose weight distribution does not extend with rotational
symmetry with respect to the rotational axis of the unbalanced
masses.
[0038] Recesses in the material of the toothed-belt pulley, being
not symmetrical with the rotational axis of the unbalanced masses,
preferably in the form of holes or bores, can effect a
non-rotationally symmetric weight distribution and can form a
negative unbalanced mass.
[0039] Laterally arranged unbalanced plates can be fastened to the
pulleys, and/or asymmetrically arranged screws can form an
imbalance weight, said screws being also adapted for attachment of
the unbalanced plates.
[0040] For accommodating the rolling bearings of the unbalanced
masses, cantilevered pivot pins can be provided, said bearings
preferably being arranged centrically to the radial belt force and
centrifugal force of the unbalanced masses.
[0041] For tensioning the belt, these bearing pins are displaceably
supported in the circles of the drum parts.
[0042] For the compacting of ground by means of a drum of a
compacting device, it is provided that, with the aid of at least
one vibration exciter comprising rotating imbalance weights,
compacting vibrations of the drum are generated, wherein, by the
use of a divided drum with two drum halves, in which the imbalance
weights of the vibration exciters in each part of the drum are
rotated by the same angle with respect to the phase position as in
the turning of the drum halves relative to each other, in order to
obtain a synchronization of the oscillatory movement of the two
drum halves even if the drum halves have been turned relative to
each other.
[0043] A mechanical connection is provided to allow for
synchronization of the exciter forces in both drum halves. This
function is fulfilled by a multi-stage planetary gear
transmission.
[0044] In this arrangement, a gear transmission has the function to
transmit, with correct phase, the moment of the hydraulic motor
provided for driving the unbalanced masses, from the left drum to
the right drum.
[0045] Embodiments of the invention will be explained in greater
detail hereunder with reference to the drawings.
[0046] The following is shown:
[0047] FIG. 1 a vibration device,
[0048] FIG. 2 a divided vibration drum of the roller DV90 according
to the state of the art,
[0049] FIG. 3 a simple toothed belt guiding arrangement for divided
oscillation by which the phase problem cannot be solved,
[0050] FIGS. 4 to 7 different drum positions,
[0051] FIG. 8 a sectional view of the drum according to the
invention,
[0052] FIG. 9 a planetary gear set,
[0053] FIG. 10 a toothed-belt transmission with omega loop,
[0054] FIG. 11 the eccentricity of the imbalance flange/bearing
pin, and
[0055] FIG. 12 a perspective view of a toothed-belt pulley.
[0056] FIG. 1 illustrates, as an example of a vibration device, a
road roller engine, namely particularly a tandem-type vibration
roller engine comprising a front and a rear drum 2.
[0057] FIGS. 2 to 7, as already mentioned in the introduction to
the specification, illustrate the state of the art.
[0058] In FIG. 8, a divided oscillatable drum 2 is shown. There are
illustrated the two drum parts 2a,2b with in-built gear
transmission, e.g. the planetary gear transmission 6 shown in FIG.
9 for solving the phase problem when negotiating curves, unbalanced
masses (imbalance weights) 3 of the vibration exciters 30a,30b, and
attachments.
[0059] Travel drives 7a,7b are provided to drive the respective
drum parts 2a,2b. The planetary gear transmission 6 comprises two
planetary gear sets 6a,6b.
[0060] Each drum part 2a,2b comprises an inner end-side ring
12a,12b in which e.g. bearing pins 20a,20b are supported for
accommodating rotatable unbalanced masses 3 of the vibration
exciters 30a,30b.
[0061] Via the bearing pin 16a and the round wall 12a, the ring
gear 10a on the left-hand side of the first planetary gear set 6a
is tightly connected to the drum part 2a on the left-hand side of
drum 2. Via the bearing pin 16b and the ring 12b, the ring gear 10b
on the right-hand side of the drum is connected to the drum part 2b
on the right-hand side of drum 2.
[0062] In FIG. 9, the configuration of a planetary gear
transmission 6 is shown.
[0063] The synchronization of the imbalance moments is independent
from the turning of the drum parts 2a,2b. For ease of explanation,
the following be assumed:
[0064] The hydraulic motor 7 for driving the oscillation movement
is running, and the drum parts 2a,2b are not in motion, i.e. both
drum parts 2a,2b are at a standstill. As a consequence, both ring
gears 10a,10b shown in FIG. 9 are blocked because, as already
described, they are connected to the drums 2a,2b in a manner fixing
them against turning.
[0065] In the planetary gear set 6a on the left-hand side in FIG.
9, the drive moment which is transmitted by the hydraulic motor 7
onto the drive shaft 5a (sun shaft), is passed on to the planet
carrier 9 via the sun gear 11a and the planetary gears 8a. What
holds true here is case 3 (sun gear driving, web outputting) of the
elementary planet gear set according to table 2. The transmission
ratio i will thus be 3.
[0066] The numbers of the teeth of the wheels of the planetary gear
set 6 for calculation of the transmission ratios are listed in
Table 1.
TABLE-US-00001 TABLE 1 Numbers of the teeth of the transmission
gears Wheel 1 2 3 sun gear planetary gear ring gear Number of teeth
40 20 80
[0067] From planet carrier 9, the moment will now be further
transmitted, via the planetary gears 8b of the right-hand stage, to
the right-hand sun gear 11b and the drive shaft (sun shaft) 5b
(FIG. 9). Since the two planetary gear sets 6a,6b are identical in
configuration, the transmission ratio i according to Table 2, case
4, will thus be 1/3 for the right-hand stage (planetary gear set
6b). In the moment transmission, this will result in a total
transmission ratio of 1 (left-hand sun gear 11a to right-hand sun
gear 11b).
[0068] Therefore, if both drum parts 2a,2b are rotating with the
same rotational speed--during travel along a linear path or during
standstill--i.e. when no turning of the drum parts 2a,2b relative
to each other occurs, the moment of rotation will be transmitted as
desired with a transmission ratio 1:1 from one side to the
other.
TABLE-US-00002 TABLE 2 Fixed to Input Case casing drive Output
Transmission ratio i 2 web ring gear sun -z1/z3 = -1/2 3 ring gear
sun web (z1 + z3)/z1 = 3 4 ring gear web sun Z1/(z1 + z3) = 1/3
[0069] In the turning of one drum part 2a relative to the other,
2b, it must be guaranteed that the unbalanced masses 3 will be
rotated along in the same extent.
[0070] For ease of explanation, the following be assumed:
[0071] The drum part 2a on one side is at a standstill, the
hydraulic motor 7 is not running. This means, put briefly, that the
ring wheel 10a of the first stage (planetary gear set 6a) which is
connected to drum part 2a, and the sun gear 11a of the first
planetary gear set 6a which via drive shaft 5a is coupled to the
hydraulic motor 7, are at a standstill. As a result, the planetary
gear set 6a on one side (the left side in FIG. 9) is blocked.
[0072] The drum part 2b on the other side is now imagined to be
rotated by a random angle.
[0073] The ring gear 10b of the planetary gear set 6b on the other
side (the right-hand side in FIG. 9) is connected, via the ring
gear driver and the bearing pin 16b, to the drum part 2b. The
latter will now transmit the rotation of drum part 2b via the
planetary gears 8b to the sun gear 11b on the right-hand side. The
common planet carrier 9, as already explained, is blocked via the
planetary gear set on the left-hand side. Thus, there holds true
case 2 of the elementary planetary gear set of Table 2. The
transmission ratio i will thus be -0.5.
[0074] As already explained, the unbalanced mass 3 has to be
rotated by the same angle as the drum part 2a,2b in which it is
supported, in order to achieve a synchronization of the oscillation
movement in both drum parts 2a,2b.
[0075] Preferably, as a planetary gear set 6, use can be made of a
two-stage planetary gear transmission comprising a belt
transmission with reversal of the rotational direction and with
reciprocal transmission ratio.
[0076] The respective ring gears 10a,10b of the planetary gear sets
6a,6b are connected to the drum parts 2a,2b for common rotation
therewith by way of bearing pins 16a,16b arranged in the adjacent
round walls 12a,12b of the drum parts 2a,2b, wherein the bearing
pins 16a,16b also form the support of the central drive pulleys 21
of the toothed-belt transmission 15a,15b for driving the vibration
exciters 30a,30b.
[0077] Alternatively, there can also be used a multi-stage
planetary gear transmission with a belt transmission ratio unequal
to the reverse value of the gear transmission and without a
reversal of directions.
[0078] Due to the guidance of the toothed belt 32c with omega loop
(see FIG. 10) and a transmission ratio of -2, there is no need for
a third planetary gear stage which would achieve a total
transmission ratio 1 and a reversal of directions. The omega loop
is to say that the toothed belt 15c encloses the toothed-belt
pulleys 13 by more than 180.degree., e.g. by more than about
200.degree. to 210.degree., particularly 205.degree., as shown in
FIG. 10.
[0079] Also here, due to the individual transmission ratios of -0.5
in the planetary gear set, and -2 in the toothed-belt transmission
15, the total transmission ratio will be 1.
[0080] Thus, the unbalanced masses 3 will be adjusted by the same
angle as the turned drum parts 2a,2b, as required. The moments
generated by the oscillation imbalances will thus be in the same
phase in each drum part 2a,2b, irrespective of the current
orientation of the unbalanced masses 3 relative to each other.
[0081] In the guiding arrangement of the toothed belts, there have
been realized some basic innovations and advantageous changes.
[0082] A belt will drive one or a plurality of imbalance shafts. If
the drive according to WO 82/201903 were applied to a divided drum
20, there would be required eight pulleys and four belts.
[0083] Here, in contrast to the previous non-divided constructions
(WO 82/201903) where each imbalance shaft is provided with its own
toothed-belt drive, both unbalanced masses 3 of a drum part 2a,2b
will be driven by one belt, preferably a toothed belt 32. Thereby,
respectively one toothed belt 32 and one drive pulley can be
omitted per drum half.
[0084] In the toothed-belt guiding arrangement, there is realized,
as already described, a transmission ratio of -2. This has been
achieved with the aid of the omega loop of the toothed belt 32
according to FIG. 10. For this purpose, the large pulleys 13
comprise twice the number of teeth as the smaller drive pulley
21.
[0085] By the deflection at the smaller drive pulley 21, the
direction of rotation is changed, which leads to the required
negative transmission ratio.
[0086] By the required transmission ratio of the toothed-belt
transmission of -2, it should preferably be possible to use a large
toothed-belt pulley 13 within which also large part of the
unbalanced mass 3 can be realized.
[0087] Since it is required anyway to drill holes into the
toothed-belt pulley 13 for screw attachment of the imbalance plates
14, additional bores 35 can be applied in order to establish a part
of the required imbalance 3 on the opposite side of the imbalance
weights in the form of unbalanced plates 14 (negative imbalance). A
further advantage resides in the smaller moment of inertia of
toothed-belt pulley 13 achieved by the reduced weight, allowing for
faster run-up when starting the drive.
[0088] The remaining portion of the unbalanced mass 3 is realized
by the lateral imbalance plates 14 and e.g. the nine screws 18
forming an imbalance weight (positive imbalance), by which the
imbalance plates 14 are--preferably on both sides--fastened to the
toothed-belt pulleys 13 (FIG. 10).
[0089] Thus, the toothed-belt pulley 13, being necessary anyway;
also serves as an unbalanced mass 3. The imbalance plates 14
arranged laterally of the toothed-belt pulley 13 are screwed
directly to the respective toothed-belt pulleys 13. The screws 18
form an additional imbalance weight. In this arrangement, the holes
or bores 35 on the side opposite to the screws 18 foam a negative
imbalance.
[0090] In FIG. 10, the two laterally fastened imbalance plates 14
are shown in the mounting position with installed toothed belt 32.
The outer contour of the imbalance plates 14 is provided to the
effect that the oblique flank 14a on the sides of the imbalance
plates 14 is in exact alignment with the short strand 32a of the
toothed belt 32. This is one possibility for visually checking the
correct 180.degree. displacement of the unbalanced masses 3 by way
of the orientation of the toothed belt 32.
[0091] The angles of the oblique flanks 14a of the imbalance plates
14 correspond to the angle of the belt 32 on the omega-enclosed
side in the position shown in FIG. 10.
[0092] The imbalance plates 14 are preferably arranged on both
sides of the toothed-belt pulley in the same position. By way of
the thickness of the imbalance plates 14, the mass of the imbalance
3 can be varied, which can also be effected via the number of the
screws 18 or the size of the bores 35.
[0093] Previously, the required belt tension of the toothed belt 32
was generated either with the aid of an additional tensioning
roller or by exclusive use of selected, well-dimensioned toothed
belts 32 having a length exactly corresponding to the
tolerances.
[0094] In the present construction shown in FIGS. 10 and 11, the
belt tension is set by continually changing the distance of the
axes between the drive shaft 5a,5b and the axis of the bearing pin
20a,20b. This is achieved by turning the eccentrically supported
bearing pin 20a,20b at the imbalance flange 19 (FIG. 11).
[0095] The turning of the eccentric imbalance flange 19 by the
bearing pin 20a,20b for tensioning the toothed belt 15c is
performed by turning an eccentric adjustment pin 17 (FIG. 10). The
latter comprises two mutually eccentric cylinders and a hexagon for
application of a wrench.
[0096] The eccentric adjustment pin 17 is provided for turning the
eccentric imbalance flange 19.
[0097] Due to the eccentricity, turning the adjustment pin 17 will
cause the imbalance flange 19 to be turned relative to the round
wall 12a,12b.
[0098] Thus, the belt 32 can be tensioned by means of an
eccentrically displaceable bearing pin arrangement.
[0099] The cantilevered bearing pin 20a,20b serves for
accommodating a rolling bearing 34 for the toothed-belt pulley 13.
The rolling bearing 34 is arranged centrically relative to the
radial belt force and centrifugal force of the unbalanced masses
3.
[0100] FIG. 12 shows a perspective view of the toothed-belt pulley
13 without toothed belt 32.
* * * * *